Prognostic role of neutrophils to lymphocytes ratio in patients with acute pulmonary embolism: a systematic review and meta-analysis of the literature

The prognostic assessment of patients with acute pulmonary embolism (PE) is essential to drive its management. The search for new prognostic factors is a central issue for a more accurate estimate of short-term adverse events. Circulating neutrophils/lymphocytes ratio (NLR) has been suggested as prognostic biomarker for different cardiovascular diseases. Given the central role of inflammation, and in particular of neutrophils in the pathogenesis of VTE and its clinical history, NLR might represent a prognostic tool also in this setting. We performed a systematic review and meta-analysis of the literature to assess the prognostic role of NLR in patients with acute PE. MEDLINE and EMBASE were searched up to 2017, week 21. A bivariate random-effects regression approach was used to obtain summary estimate of accuracy of the high NLR adjusting for inter-study variability. Six studies for a total of 1424 patient are included. High NLR has a weighted mean sensitivity of 77% (95% CI 68-83) and a weighted mean specificity of 74% (95% CI 68-79). High NLR positive and negative predictive values are 24.4% (95% CI 20.4-28.3) and 96.7% (95% CI 95.6-97.8), respectively. The relevant impact of NLR on short-term mortality after an acute PE makes it a promising biomarker to better stratify patient prognosis.